This invention relates to aortic cannula used in heart valve surgery.
More specifically, this invention relates to devices and methods for complete removal of residual air and debris from the circulatory system following cardiopulmonary bypass heart surgery before restoring normal blood circulation through the heart.
The use of cardiopulmonary bypass in heart valve surgery is a well-established method for maintaining blood circulation during open heart surgery. Cardiopulmonary bypass is accomplished by inserting one or more cannula into the vena cava, and drawing venous blood into the heart-lung machine. Oxygenated blood from the heart-lung machine is then returned to the patient""s aorta via an aortic cannula placed in the ascending aorta. The aorta is then cross-clamped immediately below the insertion site of the aortic cannula, thus isolating the aortic arch from the aortic valve. Prior to opening the ascending aorta or atrium a cold cardioplegia solution is pumped into the aorta by means of a small cannula placed in the ascending aorta below the aortic cross clamp. This is called antegrade cardioplegia delivery and results in arrest of the heart. This is often followed by a second delivery of cardioplegia solution delivered by a cannula inserted into the coronary sinus, the venous drainage vessel of the coronary. The retrograde delivery of cardioplegia flows first through the coronary veins, the myocardium and the passes into the coronary arteries hence through the coronary sinuses into the aorta. The solution exits the aorta via the retrograde cardioplegia catheter. Cardioplegia delivery often in 500 cc boluses is delivered approximately every 20 to 30 minutes to the arrested heart. Once cardiopulmonary bypass has been established and the heart arrested the aorta may be opened if the surgery is to be performed on the aortic valve, or the left atrium if surgery is to be performed on the mitral valve. Following the completion of valve surgery, the aorta or atria are closed, and the task of removing air in the atrium, ventricle and aorta falls to the surgeon. Milsom P F, and Mitchell S. J. A dual-vent left heart deairing technique markedly reduces carotid artery microemboli. Ann Thorac Surg. September 1998;66(3):785-91, describe a method for reducing microemboli. A further source of microemboli not discussed by Milson may be shed from the site of the aortic cross clamp, in patients with arterioscerotic plaque in the aorta.
This invention provides for the aortic venting method described by Milsom, obviates and aortic cross clamp by using an occlusive balloon in the ascending aorta.
Cannula and occluder devices for redirecting the blood are, of course, known. For example, Macoviak, et. al. U.S. Pat. Nos. 5,833,671, 5,827,231 and 6,059,757 disclose various catheters with retrograde and antegrade fluid flow. U.S. Pat. Nos. 6,048,331 and 6,176,851 to Tsugita and Maahs disclose a device for occluding a vessel and performing other functions which provides cannula for selectively introducing cardioplegia solution or for withdrawing blood, emboli, etc. from one side of the occluder. Tsugita and Maahs suggest a xe2x80x9cone stickxe2x80x9d device but the device suggested is a combination of two devices through the same incision in the aorta. Davis, et. al. U.S. Pat. Nos. 6,068,608 and 6,132,397 disclose an aortic arch infusion clamp which has plural lumina but does not contemplate and is not useful for removing air or debris from the surgical site following open heart surgery.
It is an object of this invention to provide a multi-luminal device to permit bypass flow to continue and, for a period at the same time, to expel blood, along with air or particle emboli, using the beating heart as the pump.
The present invention is a device and method for redirecting arterial blood flow on one side of an occluder and simultaneously removing blood containing air emboli on the other side of the occluder through a passage approximately the same cross-sectional flow area as the arterial delivery area, thus providing in one simple device means for isolating the proximal and distal ascending aorta.
The invention is embodied in a unitary device comprising an L curved cannulated body having proximal and distal ends that includes two approximately flow cross-sectional lumina of a size large enough to maintain bypass circulation, a balloon occluder secured around the distal, shorter, end of the cannulated body, the first lumen opening at the distal end of the cannulated body such that, in use, the first lumen is in fluid communication with the vessel on a first side distal of the occluder to maintain bypass circulation in the vessel a second lumen having an opening that, in use, is in fluid communication with a second side proximal of the occluder and a fluid conduct for inflating the balloon occluder to form a seal with the vessel in which, in use, the occluder resides for preventing fluid flow in the vessel from one side of the occluder to the other side of the occluder.
The invention is also embodied in an improvement in methods of performing cardiopulmonary bypass heart surgery in which the flow of blood of a patient from the venous system is bypassed to an oxygenator and the needed surgery is done to the valves or other structures of the heart. In this sense, this is an improvement over the methods described by Milsom et. al. and in the very extensive literature on open heart surgery. The improvement comprises inserting into the ascending aorta of the patient a cannulated body having a proximal end and a distal end and being curved adjacent the distal end, said cannulated body being constructed and configured to define a first curved lumen having a proximal end and a distal end and a second lumen having a proximal end and a distal inlet formed in the cannulated body such that when in use, the inlet is proximate the termination of flow in the aorta of blood from the heart and means for causing the occluder to expand or to contract. The surgical procedure is performed, the flow of blood from the venous system into the heart is restored and the heart is restarted, pumping blood into the ascending aorta. Blood pumped by the heart is removed from the aorta through the inlet in the cannulated body to remove air or other emboli. Once the air or other emboli are removed, the cannulated body is removed from the ascending aorta and the incision closed.
Briefly, as a device, the invention is a cannulated body having a proximal end for, in use, residing outside a blood vessel and a distal end for, in use, residing inside a blood vessel, the cannulated body being curved adjacent the distal end, an expandable occluder secured around the cannulated body proximate the distal end thereof, the cannulated body being constructed and configured to define a first curved lumen having a proximal end and a distal end, and a second lumen having a proximal end and a distal inlet formed in the cannulated body adjacent the proximal side of the occluder.